Auxiliary artificial heart pump drive device and auxiliary artificial heart system

ABSTRACT

An auxiliary artificial heart pump drive device for driving an auxiliary artificial heart pump includes first and second pump control parts which are arranged in duplexed configuration. Each pump control part controls the auxiliary artificial heart pump by outputting a drive signal to the auxiliary artificial heart pump. Each pump control part has a means which, when a failure is detected in the pump control part, electrically cuts off a path through which the drive signal is outputted to the auxiliary artificial heart pump. According to the present invention, it is possible to provide an auxiliary artificial heart pump drive device and an auxiliary artificial heart system which exhibit high availability even when a serious failure occurs by any chance without duplexing a pump device.

RELATED APPLICATIONS

The present application is national phase of International ApplicationNumber PCT/JP2009/055538 filed Mar. 22, 2009, and claims priority from,Japanese Application Number 2008-077953 filed Mar. 25, 2008.

TECHNICAL FIELD

The present invention relates to an auxiliary artificial heart pumpdrive device and an auxiliary artificial heart system which uses theauxiliary artificial heart pump drive device.

BACKGROUND OF THE INVENTION

Along with the progress of medical technology in recent years, thenumber of cases where cardiopathy which has been considered as a seriousdisease can be cured is increased. On the other hand, with respect toserious cardiopathy, at present, there may be also a case where the onlyway to cure such cardiopathy is the heart transplantation. Under suchcircumstances, a heart transplantation waiting patient has to wait for adonor who is compatible with the patient. Accordingly, there has beenalso a case where the heart transplantation cannot be promptly carriedout so that the life support of the heart transplantation waitingpatient is heavily hindered.

To cope with such a situation, there has been adopted a method in whichan auxiliary artificial heart is embedded in such a hearttransplantation waiting patient so as to assist the circulation of bloodof the patient thus allowing the heart transplantation waiting patientto wait for a donor who is compatible with the patient for a longperiod. It is expected that the life of a patient which suffers fromserious cardiopathy is helped not by a heart of a donor but by anartificial heart in future.

Such an auxiliary artificial heart includes an auxiliary artificialheart pump which functions as a blood pump for assisting functions of aleft ventricle and a right ventricle. The auxiliary artificial heart isa so-called life support device and hence, the auxiliary artificialheart pump and an auxiliary artificial heart pump drive device fordriving the auxiliary artificial heart pump are requested to exhibitextremely high reliability and availability.

Techniques which are applicable to enhance the reliability andavailability of the auxiliary artificial heart pump drive device aredisclosed in patent document 1, patent document 2, patent document 3 andnon-patent document 1, for example. Patent document 1 discloses aninverter device for driving an AC motor in which control parts areduplexed and the control parts are changed over so as to prevent theflow of an overcurrent. Patent document 2 discloses an electric vehiclecontrol device in which microprocessors which perform a vehicle controlare provided doubly, and arithmetic calculation results of therespective microprocessors are checked doubly thus outputting a normalarithmetic calculation result. Patent document 3 discloses a techniquerelating to a motor drive circuit which includes a main drive circuitand a backup drive circuit for driving a motor, and outputs a drivesignal of either one of the main drive circuit and the backup drivecircuit to a motor using a switching circuit when a failure is detectedin the main drive circuit. Non-patent document 1 discloses a redundantmotor which includes motor windings of two systems in the motor.

-   Patent document 1: JP-A-7-231697-   Patent document 2: JP-A-7-143604-   Patent document 3: JP-A-2007-83887-   Non-patent document: N. Ertugrul, W. Soong, G. Dostal and D. Saxon,    “Fault Tolerant Motor Drive System with Redundancy for Critical    Application”, IEEE Power Electronics Specialists Conference,    2002, p. 1457-1462

DISCLOSURE OF THE INVENTION Task to be Solved by the Invention

Even when an attempt to enhance availability is made by using onecontrol part constantly and by using the other control part in a standbystate as a backup at the time of the occurrence of a failure, in thetechniques disclosed in patent document 1, patent document 2 and patentdocument 3, for example, a power amplifying circuit which supplies adrive power source to the motor is used in common by the control parts.Accordingly, there arises a drawback that when a failure occurs in thepower amplifying circuit, the driving of an auxiliary artificial heartpump becomes uncontrollable so that the reliability of an auxiliaryartificial heart is lowered and also the availability of the auxiliaryartificial heart is not enhanced. Further, in the technique disclosed innon-patent document 1, for example, it is necessary to multiplex a motorside and hence, an auxiliary artificial heart pump becomes large-sizedthus making the application of this technique to the auxiliaryartificial heart pump substantially impossible.

In this manner, with the mere technique where the circuits are simplyconnected with each other in parallel as in the case of the prior art,there exists a possibility that the circuit of a back-up-side system isaffected by the circuit of the failure system so that the circuit of theback-up-side system does not function normally.

The present invention has been made in view of the above-mentionedtechnical drawbacks, and it is an object of the present invention toprovide an auxiliary artificial heart pump drive device and an auxiliaryartificial heart system which exhibit high availability even when aserious failure occurs by any chance without duplexing a pump device.

Means for Solving the Task

To overcome the above-mentioned drawbacks, the present inventionprovides an auxiliary artificial heart pump drive device for driving anauxiliary artificial heart pump which includes first and second pumpcontrol parts arranged in duplexed configuration, and each pump controlpart controls the auxiliary artificial heart pump by outputting a drivesignal to the auxiliary artificial heart pump. Each pump control partalso has a means which, when a failure is detected in the pump controlpart, electrically cuts off a path through which the drive signal isoutputted to the auxiliary artificial heart pump.

According to the present invention, even when a failure occurs in thefirst or second pump control part, the failure which occurs in one pumpcontrol part does not influence the other pump control part.Accordingly, the auxiliary artificial heart pump drive device cancontinue the driving of the auxiliary artificial heart pump whilemaintaining a normal operation state thus realizing high availability.For example, when a failure occurs in one pump control part (forexample, the first pump control part) not only in an open mode but alsoin a short-circuiting mode, it is possible to prevent the occurrence ofa state where an output line of the other pump control part (forexample, the second pump control part) is fixed to a ground level sothat the other pump control part (for example, the second pump controlpart) cannot perform a drive control of the auxiliary artificial heartpump.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, each pump control part may have a means whichstops the supply of electricity to the pump control part when a failureis detected in the pump control part.

According to the present invention, since the supply of electricity tothe pump control part is stopped when a failure is detected in the pumpcontrol part, even when a failure occurs in the first or second pumpcontrol part, it is possible to surely prevent the failure in one pumpcontrol part from influencing the other pump control part so that theauxiliary artificial heart pump can be continuously driven thus furtherenhancing availability of the auxiliary artificial heart pump drivedevice.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, the means which stops the supply ofelectricity may be a unidirectional switch circuit which is connected toa power source line which supplies electricity to the auxiliaryartificial heart pump drive device.

According to the present invention, the constitution of the auxiliaryartificial heart pump drive device can be simplified without adoptingthe complicated constitution and hence, it is possible to enhance theavailability of the auxiliary artificial heart pump drive device withoutlowering the reliability of the auxiliary artificial heart pump drivedevice.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, the unidirectional switch circuit may beconstituted of a metal oxide film semiconductor field effect transistor.

According to the present invention, since the semiconductor switchrealized by the metal oxide film semiconductor field effect transistoris adopted as the unidirectional switch circuit, even when a failureoccurs in the semiconductor switch per se by any chance, most of thefailure is a failure in a short-circuiting mode whereby unless doublefailures consisting of this failure and a failure in the pump controlpart occur, the failure does not influence the driving of the auxiliaryartificial heart pump so that the reliability of the auxiliaryartificial heart pump drive device can be remarkably enhanced.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, each pump control part may include a poweramplifier which amplifies power of the drive signal and a bidirectionalswitch circuit which is provided between an output of the poweramplifier and the auxiliary artificial heart pump, and when the firstpump control part is in a normal state, the bidirectional switch circuitof the first pump control part may be set in a conductive state and thebidirectional switch circuit of the second pump control part may be setin a cut-off state, and when the first pump control part is in a failurestate, the bidirectional switch circuit of the first pump control partmay be set in a cut-off state and the bidirectional switch circuit ofthe second pump control part may be set in a conductive state.

According to the present invention, the constitution of the auxiliaryartificial heart pump drive device can be simplified without adoptingthe complicated constitution and hence, it is possible to enhance theavailability of the auxiliary artificial heart pump drive device withoutlowering the reliability of the auxiliary artificial heart pump drivedevice.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, the power amplifier may be an invertercircuit.

According to the present invention, the constitution of the auxiliaryartificial heart pump drive device can be simplified and, further, evenwhen a failure occurs by any chance, most of the failure is a failure ina short-circuiting mode and hence, unless double failures occur, theauxiliary artificial heart pump drive device can continue driving of theauxiliary artificial heart pump while maintaining a normal operationstate thus acquiring high availability.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, the bidirectional switch circuit may beconstituted of a metal oxide film semiconductor field effect transistor.

According to the present invention, since the semiconductor switchrealized by the metal oxide film semiconductor field effect transistoris adopted as the bidirectional switch circuit, even when a failureoccurs in the semiconductor switch per se by any chance, most of thefailure is a failure in a short-circuiting mode whereby unless doublefailures occur, the failure does not influence the driving of theauxiliary artificial heart pump thus largely enhancing the reliabilityof the auxiliary artificial heart pump drive device.

In the auxiliary artificial heart pump drive device according to thepresent invention, each pump control part includes a detection circuitfor detecting a failure in the pump control part, and can electricallycut off a path through which the drive signal is outputted to theauxiliary artificial heart pump from the pump control part when thefailure in the pump control part is detected by the detection circuit.

According to the present invention, it is possible to provide theauxiliary artificial heart pump drive device having high availabilityeven when a serious failure occurs by any chance without duplexing thepump device.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, the detection circuit can detect a failure inthe pump control part using at least one monitoring result out of anovercurrent of a power source line for supplying electricity to theauxiliary artificial heart pump drive device, an overvoltage of thepower source line and a temperature near the pump control part.

According to the present invention, an estimated failure factor ismonitored, and when a failure is detected by any chance, the switchingof the system is rapidly performed thus providing the auxiliaryartificial heart pump drive device which exhibits high reliability andhigh availability.

Further, in the auxiliary artificial heart pump drive device accordingto the present invention, assuming a detection period for detecting thepresence or non-presence of a failure based on the overcurrent of thepower source line as T1, a detection period for detecting the presenceor non-presence of a failure based on the overvoltage of the powersource line as T2, and a detection period for detecting the presence ornon-presence of a failure based on the temperature near the pump controlpart as T3, the detection periods may satisfy the relationship ofT1<T2<T3.

According to the present invention, by performing the failuredetermination such that the detection period for detecting theovercurrent becomes shortest among three kinds of detection periods, thesystem can be rapidly switched with respect to the failure factor whichis difficult to avoid and is more serious thus enhancing theavailability of the auxiliary artificial heart pump drive device.Further, by performing the failure determination such that the detectionperiod for detecting the temperature near the pump control part becomeslongest among three kinds of detection periods, with respect to thecountermeasure against the failure factor which brings about a seriousfailure when the failure occurs but has a long cycle of change, theorder of priority assigned to the failure factor is lowered so that theauxiliary artificial heart pump drive device can rapidly cope with otherfailure factors thus enhancing the availability of the auxiliaryartificial heart pump drive device.

Further, the present invention relates to an auxiliary artificial heartsystem for assisting the flow of blood in a heart, wherein the auxiliaryartificial heart system includes an auxiliary artificial heart pump, andany one of the above-mentioned auxiliary artificial heart pump drivedevices for driving the auxiliary artificial heart pump.

According to the present invention, it is possible to provide anauxiliary artificial heart system which exhibits high availability evenwhen a serious failure occurs by any chance without duplexing the pumpdevice.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a view showing a constitutional example of an auxiliaryartificial heart system according to an embodiment of the presentinvention.

FIG. 2 is a view showing one example of a cross-section of an auxiliaryartificial heart pump according to the embodiment.

FIG. 3 is a block diagram showing a constitutional example of anauxiliary artificial heart pump drive device in a control unit accordingto the embodiment.

FIG. 4 is a circuit diagram of a constitutional example of first andsecond inverter circuits, first and second switch circuits and first andsecond power source switches of the auxiliary artificial heart pumpdrive device shown in FIG. 3.

FIG. 5 is an explanatory view of a gate signal of the first invertercircuit shown in FIG. 4.

FIG. 6 is a circuit diagram of a constitutional example of abidirectional switch circuit of the first switch circuit shown in FIG.4.

FIG. 7 is an operational explanatory view of a gate driver providedcorresponding to the bidirectional switch circuit shown in FIG. 6.

FIG. 8 is an explanatory view of a control example of the first and thesecond switch circuits and the first and the second power sourceswitches shown in FIG. 4.

FIG. 9 is a block diagram of a hardware constitutional example of afirst processing circuit of a first pump control part according to theembodiment.

FIG. 10 is a flowchart of a processing example of the first processingcircuit shown in FIG. 9.

FIG. 11 is an explanatory view of detection periods shown in FIG. 10.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention is explained indetail in conjunction with drawings. The embodiment explainedhereinafter does not unduly limit contents of the present inventiondescribed in Claims. Further, all constitutions explained hereinafter donot always constitute inevitable constitutional elements of the presentinvention.

FIG. 1 shows a constitutional example of an auxiliary artificial heartsystem according to an embodiment of the present invention.

The auxiliary artificial heart system (a pump system, a motor system inbroad meaning) 100 according to this embodiment includes an auxiliaryartificial heart pump (a pump, a motor in broad meaning) 10 and acontrol unit 20. The auxiliary artificial heart pump 10 and the controlunit 20 are connected with each other via a cable 30.

The auxiliary artificial heart pump 10 is a blood pump which assists afunction of a left ventricle of a heart and is embedded in the inside ofa human body. As such an auxiliary artificial heart pump 10, apulsation-flow-type blood pump which imparts a predetermined cycle tothe flow of blood to be circulated may be adopted or acontinuous-flow-type blood pump which produces the continuous flow ofblood to be circulated may be adopted.

The control unit 20 includes a power source PS and an auxiliaryartificial heart pump drive device (a pump drive device, a motor drivedevice in broad meaning) CONT and is provided outside the body. Thepower source PS supplies a power source voltage to the auxiliaryartificial heart pump drive device CONT from any one of an AC powersource, a built-in battery and an emergency battery via a power sourceline VL. The auxiliary artificial heart pump drive device CONT generatesa drive current (a drive signal in broad meaning) which drives theauxiliary artificial heart pump 10 in a state where a power sourcevoltage from the power source PS is supplied. The cable 30 has a signalline through which a drive current for driving the auxiliary artificialheart pump 10 from the control unit 20 is transmitted.

FIG. 2 shows one example of a cross section of the auxiliary artificialheart pump 10 according to this embodiment. Although FIG. 2 shows aconstitutional example of the auxiliary artificial heart pump 10, thisembodiment is not limited to the auxiliary artificial heart pump havingthe constitution shown in FIG. 2.

The auxiliary artificial heart pump 10 includes a drive part 11 whichhas a cylindrical motor and a pump part 12 which is connected to thedrive part 11. The pump part 12 includes an impeller 13 which is drivenby way of a rotary shaft of the motor, and a pump casing 14 which isconnected to the drive part 11 in a state where the pump casing 14covers the impeller 13. The auxiliary artificial heart pump 10 isconfigured such that when blood in a left ventricle of a heart flowsinto the pump casing 14 via a blood vessel (artificial blood vessel) andan inlet port 15, after flow energy is imparted by the impeller 13, theblood flows out to an aorta via an outlet port 16 formed in a sidesurface of the pump casing 14 and a blood vessel (artificial bloodvessel).

In the auxiliary artificial heart pump 10, a mechanical seal part 17 isarranged between the drive part 11 and the pump part 12. Accordingly,the pump part 12 and the drive part 11 are slidably and firmly sealedfrom each other thus suppressing leaking of the blood from the pump part12 to the drive part 11 as much as possible. As a result, the generationof a blood clot is suppressed thus suppressing stopping of an operationof the pump and a change in an operational state of the pump.

The pump part 12 is a centrifugal pump by which a larger blood flow ratecan be expected than an axial flow pump, wherein an AC motor can be usedas a motor for driving the impeller 13.

When the auxiliary artificial heart pump 10 is constituted as shown inFIG. 2, the control unit 20 shown in FIG. 1 further has a means forcirculating a cool sealing liquid which suppress the coagulation ofblood in the mechanical seal part and the generation of heat in thedrive part 11 and the motor part 12. In this case, a circulation passagefor the cool sealing liquid is formed by way of the cable 30.

Such an auxiliary artificial heart system 100 is, since it is alwaysnecessary to circulate blood by the auxiliary artificial heart pump 10,requested to exhibit both high reliability and high availability.Accordingly, not only the auxiliary artificial heart pump 10 isrequested to exhibit reliability and availability, but also theauxiliary artificial heart pump drive device CONT which constitutes thecontrol unit 20 is requested to exhibit reliability and availability. Inview of such a circumstance, this embodiment provides an auxiliaryartificial heart pump drive device CONT which provides high availabilityby continuing a pump operation of the auxiliary artificial heart pump 10even when a serious failure occurs due to a failure in the auxiliaryartificial heart pump drive device CONT or the like.

FIG. 3 is a block diagram of a constitutional example of the auxiliaryartificial heart pump drive device CONT of the control unit 20 accordingto this embodiment. In FIG. 3, parts identical with the parts shown inFIG. 1 are given same symbols and the explanation of these parts isomitted when appropriate.

In FIG. 3, the auxiliary artificial heart pump 10 includes a 3-phase ACmotor driven by a three-phase drive current. The auxiliary artificialheart pump drive device CONT generates a 3-phase (U phase, V phase, Wphase) drive current (drive signal in broad meaning) for the auxiliaryartificial heart pump 10, and controls driving of the auxiliaryartificial heart pump 10. To be more specific, the auxiliary artificialheart pump drive device CONT includes first and second pump controlparts 200, 300 arranged in duplexed configuration, wherein each pumpcontrol part generates a three-phase drive current for the auxiliaryartificial heart pump 10 and controls the driving of the auxiliaryartificial heart pump 10. Here, the first pump control part 200 isconnected with an output signal line which outputs a drive current tothe auxiliary artificial heart pump 10, the second pump control part 300is connected to an output signal line which outputs a drive current tothe auxiliary artificial heart pump 10, and the drive current which isgenerated by either one of the pump control parts is supplied to theauxiliary artificial heart pump 10.

The auxiliary artificial heart pump drive device CONT includes a pumpdrive processing circuit 400, and the pump drive processing circuit 400controls the first and second pump control parts (first and second motorcontrol parts in broad meaning) 200, 300 having the above-mentionedconstitution.

The first pump control part 200, in a normal state, functions as a pumpcontrol part of a main system which controls the driving of theauxiliary artificial heart pump 10 by generating a three-phase drivecurrent for the auxiliary artificial heart pump 10. On the other hand,the second pump control part 300, in a failure state where a failure isdetected in the first pump control part 200, functions as a pump controlpart of a backup system which controls the driving of the auxiliaryartificial heart pump 10 by generating a three-phase drive current forthe auxiliary artificial heart pump 10.

The first pump control part 200 includes a first processing circuit(first detection circuit) 210, a first gate driver 220, a first invertercircuit (power amplifier) 230, a first switch circuit 240, a firsttemperature sensor 250, and a first power source switch LDSW1.

To the first processing circuit 210, the first gate driver 220 and thefirst inverter circuit 230, as a power source voltage, a voltagesupplied to a power source line VL is supplied via the first powersource switch LDSW1. Further, a first pump drive control signal PCNT1 issupplied to the first processing circuit 210 and the first switchcircuit 240, and operations of these circuits are controlled in responseto the first pump drive control signal PCNT1.

The first processing circuit 210 detects the presence or non-presence ofa failure in the first pump control part 200. To be more specific, thefirst processing circuit 210 detects the presence or non-presence of afailure in the first pump control part 200 based on at least onemonitored result among a voltage VM₁ of the power source line VL, acurrent IM₁ of the power source line VL and a sensing result of a firsttemperature sensor 250 supplied to the first pump control part 200. Forexample, when it is detected that the voltage VM₁ exceeds apredetermined threshold value for a predetermined period based on theresult of monitoring the voltage VM₁ of the power source line VL, thefirst processing circuit 210 determines that the voltage of the powersource line VL is an overvoltage thus detecting a failure in the firstprocessing circuit 210. Further, for example, when it is detected thatthe current IM₁ exceeds a predetermined threshold value for apredetermined period based on the result of monitoring the current IM₁of the power source line VL, the first processing circuit 210 determinesthat the current of the power source line VL is an overcurrent thusdetecting a failure in the first processing circuit 210. Still further,for example, when it is detected that a temperature detected by thefirst temperature sensor 250 exceeds a predetermined threshold value fora predetermined period based on a sensing result of the firsttemperature sensor 250, the first processing circuit 210 detects afailure in the first processing circuit 210.

A detection result of the first processing circuit 210 is outputted tothe pump drive processing circuit 400 as a detection signal FAIL1. Thepump drive processing circuit 400 outputs a first pump drive controlsignal PCNT1 to the first pump control part 200 thus performing acontrol of operating or stopping the first pump control part 200.

Further, the first processing circuit 210 is configured to generate apulse width modulation (PWM) signal and to output the signal to thefirst gate driver 220. To be more specific, the first processing circuit210 monitors amplitudes and phases of a drive current IU (U-phase drivecurrent) and IV (V-phase drive current) for the auxiliary artificialheart pump 10, and generates a PWM signal for controlling amplitudes andphases of three-phase drive current to be outputted by changing pulsewidths of the drive currents in response to the monitored amplitudes andphases.

The first gate driver 220, upon receiving the PWM signal from the firstprocessing circuit 210, generates a gate signal for a first invertercircuit 230 for amplifying the drive current for the auxiliaryartificial heart pump 10. The first inverter circuit 230 generates thethree-phase drive current which is amplified based on the gate signalfrom the first gate driver 220. To suppress a penetration current at thetime of performing a power amplifying operation in the first invertercircuit 230, in response to the PWM signal, the first gate driver 220generates gate signals whose change timings do not agree with each othersuch that fall timing at which a power level is shifted from H level toL level and rise timing at which a power level is shifted from L levelto H level from do not take place simultaneously.

The first switch circuit 240, based on the first pump drive controlsignal PCNT1, electrically connects signal lines through which thethree-phase drive current amplified by the first inverter circuit 230are supplied with motor wirings of the auxiliary artificial heart pump10 or cuts off such an electrical connection. That is, the first pumpcontrol part 200 includes a means which electrically cuts off a paththrough which the three-phase drive current is outputted to theauxiliary artificial heart pump 10, and electrically cuts off the pathin response to the first pump drive control signal PCNT1 when a failureis detected in the first processing circuit 210.

The first temperature sensor 250 detects a temperature near the firstpump control part 200. To be more specific, the first temperature sensor250 detects the temperature near the first inverter circuit 230. Adetection result of the first temperature sensor 250 is notified to thefirst processing circuit 210.

The first power source switch LDSW1 has one end thereof electricallyconnected to the power source line VL and the other end thereofelectrically connected to the first processing circuit 210, the firstgate driver 220 and the first inverter circuit 230 which constitute thefirst pump control part 200. Then, a voltage of the power source line VLis supplied as a power source voltage for the first processing circuit210, the first gate driver 220 and the first inverter circuit 230 whichconstitute the first pump control part 200 via the first power sourceswitch LDSW1. The first power source switch LDSW1 is subject to anON/OFF control in response to the first pump drive control signal PCNT1.

The second pump control part 300 includes a second processing circuit(second detection circuit) 310, a second gate driver 320, a secondinverter circuit (power amplifier) 330, a second switch circuit 340, asecond temperature sensor 350, and a second power source switch LDSW2.

To the second processing circuit 310, the second gate driver 320 and thesecond inverter circuit 330, as a power source voltage, a voltagesupplied to a power source line VL is supplied via the second powersource switch LDSW2. Further, a second pump drive control signal PCNT2is supplied to the second processing circuit 310 and the second switchcircuit 340, and operations of these circuits are controlled in responseto the second pump drive control signal PCNT2.

The second processing circuit 310 detects the presence or non-presenceof a failure in the second pump control part 300. To be more specific,the second processing circuit 310 detects the presence or non-presenceof a failure in the second pump control part 300 based on at least onemonitored result among a voltage VM₂ of the power source line VL, acurrent IM₂ of the power source line VL and a sensing result of a secondtemperature sensor 350 supplied to the second pump control part 300. Forexample, when it is detected that the voltage VM₂ exceeds apredetermined threshold value for a predetermined period based on theresult of monitoring the voltage VM₂ of the power source line VL, thesecond processing circuit 310 determines that the voltage of the powersource line VL is an overvoltage thus detecting a failure in the secondprocessing circuit 310. Further, for example, when it is detected thatthe current IM₂ exceeds a predetermined threshold value for apredetermined period based on the result of monitoring the current IM₂of the power source line VL, the second processing circuit 310determines that the current of the power source line VL is anovercurrent thus detecting a failure in the second processing circuit310. Still further, for example, when it is detected that a temperaturedetected by the second temperature sensor 350 exceeds a predeterminedthreshold value for a predetermined period based on a sensing result ofthe second temperature sensor 350, the second processing circuit 310detects a failure in the second processing circuit 310.

A detection result of the second processing circuit 310 is outputted tothe pump drive processing circuit 400 as a detection signal FAIL2. Thepump drive processing circuit 400 outputs a first pump drive controlsignal PCNT1 thus performing a control for operating or stopping thesecond pump control part 300 in response to the second pump drivecontrol signal PCNT2 which is a signal reversed from the first pumpdrive control signal PCNT1.

Further, the second processing circuit 310 is configured to generate aPWM signal and to output the signal to the second gate driver 320. To bemore specific, the second processing circuit 310 monitors amplitudes andphases of a drive current IU (U-phase drive current) and IV (V-phasedrive current) for the auxiliary artificial heart pump 10, and generatesa PWM signal for controlling amplitudes and phases of three-phase drivecurrent to be outputted in response to the monitored pulse widths.

The second gate driver 320, upon receiving the PWM signal from thesecond processing circuit 310, generates a gate signal for a secondinverter circuit 330 for amplifying the drive current for the auxiliaryartificial heart pump 10. The second inverter circuit 330 generates thethree-phase drive current which is amplified based on the gate signalfrom the second gate driver 320. To suppress a penetration current atthe time of performing a power amplifying operation in the secondinverter circuit 330, in response to the PWM signal, the second gatedriver 320 generates gate signals whose change timing do not agree witheach other such that fall timing at which a power level is shifted fromH level to L level and rise timing at which a power level is shiftedfrom L level to H level do not take place simultaneously.

The second switch circuit 340, based on the second pump drive controlsignal PCNT2, electrically connects signal lines through which thethree-phase drive current amplified by the second inverter circuit 330are supplied with motor wirings of the auxiliary artificial heart pump10 or cuts off such an electrical connection. That is, the second pumpcontrol part 300 includes a means which electrically cuts off a paththrough which the three-phase drive current is outputted to theauxiliary artificial heart pump 10, and electrically cuts off the pathin response to the second pump drive control signal PCNT2 when a failureis detected in the second processing circuit 310.

The second temperature sensor 350 detects a temperature near the secondpump control part 300. To be more specific, the second temperaturesensor 350 detects the temperature near the second inverter circuit 330.A detection result of the second temperature sensor 350 is notified tothe second processing circuit 310.

The second power source switch LDSW2 has one end thereof electricallyconnected to the power source line VL and the other end thereofelectrically connected to the second processing circuit 310, the secondgate driver 320 and the second inverter circuit 330 which constitute thesecond pump control part 300. Then, a voltage of the power source lineVL is supplied as a power source voltage for the second processingcircuit 310, the second gate driver 320 and the second inverter circuit330 which constitute the second pump control part 300 via the secondpower source switch LDSW2. The second power source switch LDSW2 issubject to an ON/OFF control in response to the second pump drivecontrol signal PCNT2.

A signal line through which the first pump drive control signal PCNT1 istransmitted is pulled up so that the first pump drive control signalPCNT1 at H level is transmitted to the first pump control part 200unless the pump drive processing circuit 400 outputs the first pumpdrive control signal PCNT1 at L level. Accordingly, in an initial state,the first pump drive control signal PCNT1 assumes H level and the secondpump drive control signal PCNT2 assumes L level. Accordingly, the firstpower source switch LDSW1 is turned on so that electricity is suppliedto respective parts of the first pump control part 200, while the secondpower source switch LDSW2 is turned off so that operations of therespective parts of the second pump control part 300 are stopped. Then,when a failure in the first pump control part 200 is detected inresponse to the detection signal FAIL1, the pump drive processingcircuit 400 sets the first pump drive control signal PCNT1 at L level.Accordingly, the second pump drive control signal PCNT2 assumes H levelso that the first power source switch LDSW1 is turned off whereby theoperations of the respective parts of the first pump control part 200are stopped, and the second power source switch LDSW2 is turned onwhereby electricity is supplied to the respective parts of the secondpump control part 300 so that these parts are operated.

When a failure in the first pump control part 200 is detected inresponse to the detection signal FAIL1, the pump drive processingcircuit 400 notifies an alarm state to the outside and urges thereplacement of the control unit 20 (auxiliary artificial heart pumpdrive device CONT). The second pump control part 300 continues thedriving of the auxiliary artificial heart pump while maintaining anormal operation state until the control unit 20 is replaced. Further,when a failure in the second pump control part 300 is detected inresponse, to a detection signal FAIL2 by any chance, the pump driveprocessing circuit 400 operates so as to continue the driving of theauxiliary artificial heart pump as much as possible by performingprocessing such as the lowering of a pump drive rotational speed, forexample.

In this manner, the first pump control part 200 may include a firstswitch circuit 240 as a means which electrically cuts off a path throughwhich a drive signal is outputted to the auxiliary artificial heart pump10 when a failure is detected in the first pump control part 200.Further, the second pump control part 300 may include a second switchcircuit 340 as a means which electrically cuts off a path through whicha drive signal is outputted to the auxiliary artificial heart pump 10when a failure is detected in the second pump control part 300.

Due to such a constitution, even when a failure occurs in the first orsecond pump control part 200, 300, the failure in one pump control partdoes not influence the other pump control part and hence, the auxiliaryartificial heart pump drive device can continue the driving auxiliaryartificial heart pump 10 while maintaining a normal operation state.Particularly, as a failure mode of the first or second pump control part200, 300, an open mode where an output or an inner node of the first orsecond pump control part 200, 300 assumes a floating state and ashort-circuiting mode where a power source line and a ground line areshort-circuited to each other are named. Accordingly, this embodimentcan avoid the situation where when a failure occurs in one pump controlpart (for example, the first pump control part 200) in ashort-circuiting mode, an output line of the other pump control part(for example, the second pump control part 300) is fixed to a groundlevel so that the other pump control part (for example, the second pumpcontrol part 300) cannot perform a drive control of the auxiliaryartificial heart pump 10.

Further, the first pump control part 200 may include the first powersource switch LDSW1 as a means which stops the supply of electricity tothe first pump control part 200 when a failure is detected in ashort-circuiting mode or an open mode in the first pump control part200. Further, the second pump control part 300 may include the secondpower source switch LDSW2 as a means which stops the supply ofelectricity to the second pump control part 300 when a failure isdetected in a short-circuiting mode or an open mode in the second pumpcontrol part 300.

Due to such a constitution, even when a failure occurs in the first orsecond pump control part 200, 300, by continuing the driving of theauxiliary artificial heart pump 10 in such a manner that the other pumpcontrol part is surely prevented from being influenced by the failure inone pump control part, it is possible to further enhance theavailability of the auxiliary artificial heart pump drive device CONT.Also in this case, it is possible to surely avoid a situation where whena failure occurs in one pump control part (for example, the first pumpcontrol part 200) in a short-circuiting mode, an output line of theother pump control part (for example, the second pump control part 300)is fixed to a ground level so that the other pump control part (forexample, the second pump control part 300) cannot perform a drivecontrol of the auxiliary artificial heart pump 10.

Next, a specific constitutional example of the auxiliary artificialheart pump drive device CONT shown in FIG. 3 which performs a controlfor enhancing such availability is explained.

FIG. 4 shows a circuit diagram of a constitutional example of the firstand second inverter circuits 230, 330, the first and second switchcircuits 240, 340 and the first and second power source switches LDSW1,LDSW2 of the auxiliary artificial heart pump drive device CONT shown inFIG. 3. In FIG. 4, parts identical with the parts shown in FIG. 3 aregiven same symbols and the explanation of these parts is omitted whenappropriate.

The first power source switch LDSW1 is a unidirectional switch circuitand is constituted of a metal oxide semiconductor field effecttransistor (MOSFET). To be more specific, the MOSFET which has a drainthereof connected to the power source line VL and a source thereofconnected to the power source line of the first inverter circuit 230functions as the first power source switch LDSW1. Further, an anodeterminal of a diode element is connected to a source of the MOSFET and acathode terminal of the diode element is connected to a drain of theMOSFET.

Further, in this embodiment, the first power source switch LDSW1includes agate driver GD1, and the gate driver GD1 generates a gatesignal for a switch constituted of the MOSFET in response to the firstpump drive control signal PCNT1. To be more specific, the gate driverGD1 generates a gate signal for the MOSFET such that the MOSFET assumesa conductive state when a power level of the first pump drive controlsignal PCNT1 is at H level, and the MOSFET assumes a cut-off state whenthe power level of the first pump drive control signal PCNT1 is at Llevel.

The first inverter circuit 230 is constituted such that invertercircuits are provided corresponding to the respective phases of thethree-phase drive current. The inverter circuit is constituted byinserting a circuit in which n-type (first conductive type in broadmeaning) MOSFETs are connected in series between a ground line and asource of a MOSFET of the first power source switch LDSW1. To be morespecific, one inverter circuit includes, corresponding to the U phase,the MOSFET(Q1) in which a gate signal G11 is supplied to a gate and asource of a MOSFET of the first power source switch LDSW1 is connectedto a drain, and the MOSFET(Q2) in which a drain is connected to thesource of the MOSFET(Q1), a gate signal G12 is supplied to a gate, and aground line is connected to a source. In the same manner, anotherinverter circuit includes, corresponding to the V phase, the MOSFET(Q3)in which a gate signal G13 is supplied to a gate and the source of theMOSFET of the first power source switch LDSW1 is connected to a drain,and the MOSFET(Q4) in which a drain is connected to the source of theMOSFET(Q3), a gate signal G14 is supplied to a gate, and a ground lineis connected to a source. Further, another inverter circuit includes,corresponding to the W phase, the MOSFET(Q5) in which a gate signal G15is supplied to a gate and the source of the MOSFET of the first powersource switch LDSW1 is connected to a drain, and the MOSFET(Q6) in whicha drain is connected to the source of the MOSFET(Q5), a gate signal G16is supplied to a gate, and a ground line is connected to a source. Inthe respective MOSFETs (Q1 to Q6) which constitute the first invertercircuit 230, a diode element in the direction shown in FIG. 4 isconnected between the source and the drain.

A U-phase drive current is taken out from a connection node between thesource of the MOSFET(Q1) and the drain of the MOSFET(Q2). A V-phasedrive current is taken out from a connection node between the source ofthe MOSFET(Q3) and the drain of the MOSFET(Q4). A W-phase drive currentis taken out from a connection node between the source of the MOSFET(Q5)and the drain of the MOSFET(Q6).

FIG. 5 is an explanatory view of gate signals in the first invertercircuit 230 shown in FIG. 4. FIG. 5 shows one example of the gatesignals G11, G12 for the MOSFETs (Q1, Q2) of the first inverter circuit230.

As shown in FIG. 5, the first gate driver 220 generates gate signalssuch that the change timings of the gate signals for the MOSFET whichare connected in series do not agree with each other. Due to such anoperation, the first inverter circuit 230 can amplify the U-phase drivesignal corresponding to the pulse widths of the gate signals G11, G12without generating a penetration current.

Although the explanation has been made with respect to the gate signalsG11, G12 in FIG. 5, the same goes for a V-phase drive current amplifiedin response to the gate signals G13, G14, and a W-phase drive currentamplified in response to the gate signals G15, G16.

The first switch circuit 240 shown in FIG. 4 is constituted ofbidirectional switch circuits which are provided corresponding torespective phases of three-phase drive current. The bidirectional switchcircuit is constituted of MOSFETs. Further, the first switch circuit 240includes gate drivers which are provided corresponding to thebidirectional switch circuits of respective phases, and the gate drivergenerates gate signals of respective MOSFETs which constitute thebidirectional switch circuit.

To be more specific, the bidirectional switch circuit includes twon-type MOSFETs whose sources are connected with each other, wherein adrain of one MOSFET is connected to an output line for a drive currentfrom the first inverter circuit 230 and a drain of the other MOSFET isconnected to a motor winding. Here, a common gate signal is supplied togates of two MOSFETs from the gate driver. Between a source and a drainof each MOSFET, a diode is connected in the direction shown in FIG. 4.The gate driver which is provided corresponding to each bidirectionalswitch circuit, in a state where a predetermined power source voltageVL1 is supplied to the gate driver, generates a gate signal such thatthe MOSFETs which constitute the bidirectional switch circuit becomeconductive with each other when a first pump drive control signal PCNT1is at H level.

FIG. 6 shows a circuit diagram of a constitutional example of thebidirectional switch circuit of the first switch circuit 240 shown inFIG. 4. Although FIG. 6 shows the constitutional example of thebidirectional switch circuit provided corresponding to a U-phase drivesignal, the bidirectional switch circuits provided corresponding todrive signals of other phases have the constitutions substantially equalto the constitution shown in FIG. 6.

FIG. 7 shows an operational explanatory view of the gate driver providedcorresponding to the bidirectional switch circuit shown in FIG. 6.Although FIG. 7 shows the operational explanatory view of the gatedriver provided corresponding to a U-phase drive signal, the gatedrivers provided corresponding to drive signals of other phases areoperated in the same manner as shown in FIG. 7.

When a first pump drive control signal PCNT1 is at H level, each gatedriver in the first switch circuit 240, as shown in FIG. 7, generates agate signal such that a gate voltage of the MOSFET has a higherpotential than a source voltage and the MOSFET is turned on. As aresult, in the bidirectional switch circuit, when a control part sidehas a higher potential than a motor winding side, a current flows in thedirection DIRT along the drain, the source and the diode element D1 ofthe MOSFET (see FIG. 6), while when the control part side has a lowerpotential than the motor winding side, a current flows in the directionDIR2 along the drain, the source and the diode element D2 of the MOSFET(see FIG. 6).

Here, when the first pump drive control signal PCNT1 is at L level, eachgate driver of the first switch circuit 240 generates a gate signal suchthat a gate voltage of the MOSFET has a lower potential than a sourcevoltage so that the bidirectional switch circuit can be electrically cutoff.

The second power source switch LDSW2 is, in the same manner as the firstpower source switch LDSW1, a unidirectional switch circuit and isconstituted of a MOSFET. To be more specific, the MOSFET which has adrain thereof connected to the power source line VL and a source thereofconnected to the power source line of the second inverter circuit 330functions as the second power source switch LDSW2. Further, an anodeterminal of a diode element is connected to a source of the MOSFET and acathode terminal of the diode element is connected to a drain of theMOSFET.

Further, in this embodiment, the second power source switch LDSW2includes a gate driver GD2, and the gate driver GD2 generates a gatesignal for a switch constituted of the MOSFET in response to the secondpump drive control signal PCNT2. To be more specific, the gate driverGD2 generates a gate signal for the MOSFET such that the MOSFET assumesa conductive state when the power level of the second pump drive controlsignal PCNT2 is at H level, and the MOSFET assumes a cut-off state whenthe power level of the second pump drive control signal PCNT2 is at Llevel.

The second inverter circuit 330 is constituted such that invertercircuits are provided corresponding to the respective phases of thethree-phase drive current. The inverter circuit is constituted byinserting a circuit in which n-type MOSFETs are connected in seriesbetween a ground line and a source of a MOSFET of the second powersource switch LDSW2. To be more specific, one inverter circuit includes,corresponding to the U phase, the MOSFET(Q11) in which a gate signal G21is supplied to a gate and a source of a MOSFET of the second powersource switch LDSW2 is connected to a drain, and the MOSFET(Q12) inwhich a drain is connected to the source of the MOSFET(Q11), a gatesignal G22 is supplied to a gate, and a ground line is connected to asource. In the same manner, another inverter circuit includes,corresponding to the V phase, the MOSFET(Q13) in which a gate signal G23is supplied to a gate and the source of the MOSFET of the second powersource switch LDSW2 is connected to a drain, and the MOSFET(Q14) inwhich a drain is connected to the source of the MOSFET(Q13), a gatesignal G24 is supplied to a gate, and a ground line is connected to asource. Further, another inverter circuit includes, corresponding to theW phase, the MOSFET(Q15) in which a gate signal G25 is supplied to agate and the source of the MOSFET of the second power source switchLDSW2 is connected to a drain, and the MOSFET(Q16) in which a drain isconnected to the source of the MOSFET(Q15), a gate signal G26 issupplied to a gate, and a ground line is connected to a source. In therespective MOSFETs (Q11 to Q16) which constitute the second invertercircuit 330, a diode element in the direction shown in FIG. 4 isconnected between the source and the drain.

A U-phase drive current is taken out from a connection node between thesource of the MOSFET(Q11) and the drain of the MOSFET(Q12). A V-phasedrive current is taken out from a connection node between the source ofthe MOSFET(Q13) and the drain of the MOSFET(Q14). A W-phase drivecurrent is taken out from a connection node between the source of theMOSFET(Q15) and the drain of the MOSFET(Q16).

The generation and the processing of gate signal in the second invertercircuit 330 are also substantially equal to the generation and theprocessing of the gate signal in the first inverter circuit 230 andhence, the explanation of the generation and processing of the gatesignal in the second inverter circuit 330 is omitted.

The second switch circuit 340 shown in FIG. 4 is, in the same manner asthe first switch circuit 240, constituted of bidirectional switchcircuits which are provided corresponding to respective phases ofthree-phase drive current. The bidirectional switch circuit isconstituted of MOSFETs. Further, the second switch circuit 340 includesgate drivers which are provided corresponding to the bidirectionalswitch circuits of respective phases, and the gate driver generates gatesignals for respective MOSFETs which constitute the bidirectional switchcircuit.

To be more specific, the bidirectional switch circuit includes twon-type MOSFETs whose sources are connected with each other, wherein adrain of one MOSFET is connected to an output line for a drive currentfrom the second inverter circuit 330 and a drain of the other MOSFET isconnected to a motor winding. Here, a common gate signal is supplied togates of two MOSFETs from the gate driver. Between a source and a drainof each MOSFET, a diode element is connected in the direction shown inFIG. 4. The gate driver which is provided corresponding to eachbidirectional switch circuit, in a state where a predetermined powersource voltage VL1 is supplied to the gate driver, generates a gatesignal such that the MOSFETs which constitute the bidirectional switchcircuit are made conductive with each other when a second pump drivecontrol signal PCNT2 is at H level.

The constitution of the bidirectional switch circuit in the secondswitch circuit 340 is substantially equal to the constitution of thebidirectional switch circuit in the first switch circuit 240 and hence,the explanation of the constitution of the bidirectional switch circuitin the second switch circuit 340 is omitted.

Accordingly, when a second pump drive control signal PCNT2 is at Hlevel, each gate driver in the second switch circuit 340 generates agate signal such that a gate voltage of the MOSFET has a higherpotential than a source voltage. As a result, in the bidirectionalswitch circuit, in the same manner as the bidirectional switch circuitof the first switch circuit 240, as shown in FIG. 6, when a control partside has a higher potential than a motor winding side, a current flowsin the direction DIR1 along the drain, the source and the diode elementD1 of the MOSFET (see FIG. 6), while when the control part side has alower potential than the motor winding side, a current flows in thedirection DIR2 along the drain, the source and the diode element D2 ofthe MOSFET (see FIG. 6).

Here, when the second pump drive control signal PCNT2 is at L level,each gate driver of the second switch circuit 340 generates a gatesignal such that a gate voltage of the MOSFET has a lower potential thana source voltage so that the bidirectional switch circuit can beelectrically cut off.

FIG. 8 is an explanatory view of an example where the first and secondswitch circuits, 240, 340 and the first and second power source switchesLDSW1, LDSW2 shown in FIG. 4 are controlled.

Contents of the control shown in FIG. 8 are realized using a first pumpdrive control signal PCNT1 which the pump drive processing circuit 400outputs.

That is, when it is detected that the first pump control part 200 is ina normal state by the first processing circuit 210 in response to adetection signal FAIL1, the pump drive processing circuit 400 performs acontrol such that, in response to a first pump drive control signalPCNT1, the first power source switch LDSW1 of the first pump controlpart 200 is brought into a conductive state thus supplying a powersource voltage from the power source line VL to the first pump controlpart 200 and, at the same time, the first switch circuit 240 directlyoutputs a drive signal amplified by the first inverter circuit 230 tomotor windings of the auxiliary artificial heart pump 10. Here, the pumpdrive processing circuit 400 brings the second power source switch LDSW2of the second pump control part 300 into a cut-off state so as toprevent the supply of a power source voltage from the power source lineVL to the second pump control part 300 and, at the same time, the secondswitch circuit 340 electrically cuts off the electric connection betweena signal line through which a drive signal is outputted and the motorwindings of the auxiliary artificial heart pump 10 from each other.

On the other hand, when it is detected that the first pump control part200 is in a failure state by the first processing circuit 210 inresponse to a detection signal FAIL1, the pump drive processing circuit400 sets the first pump drive control signal PCNT1 at L level so thatthe second pump drive control signal PCNT2 is set to H level.Accordingly, the second power source switch LDSW2 of the second pumpcontrol part 300 is brought into a conductive state thus supplying apower source voltage from the power source line VL to the second pumpcontrol part 300 and, at the same time, the second switch circuit 340directly outputs a drive signal amplified by the second inverter circuit330 to motor windings of the auxiliary artificial heart pump 10. Here,the first power source switch LDSW1 of the first pump control part 200is brought into a cut-off state so as to prevent the supply of a powersource voltage from the power source line VL to the first pump controlpart 200 and, at the same time, the first switch circuit 240electrically cuts off the electric connection between a signal linethrough which a drive signal is outputted and the motor windings of theauxiliary artificial heart pump 10 from each other.

In this embodiment, the first and second inverter circuits 230, 330which have a signal power amplification function are liable to bedamaged by an overvoltage or an overcurrent. Particularly, with respectto modes in which a failure occurs in the inverter circuit, most offailures occur in a short-circuiting mode where the inverter circuit isshort-circuited with motor windings, a power source or a ground line andhence, even when the auxiliary artificial heart pump 10 is connected tothe pump control part on a backup side, a situation where a failurestate is not overcome is maintained. However, as described above, byproviding the switch circuit which cuts off the respective outputs fromthe control parts or the power source switch which cuts off means forsupplying electricity when a failure occurs in the control part(particularly in the inverter circuit), the pump control part of thefailure system can be separated from the system and hence, the auxiliaryartificial heart pump 10 can be driven continuously using the invertercircuit on a backup side system thus allowing the auxiliary artificialheart pump drive device to exhibit high availability.

Further, a semiconductor switch which is realized by the MOSFET isadopted as the power source switch or the switch circuit and hence, evenwhen a failure occurs in the semiconductor switch per se by any chance,most of failures are failures in a short-circuiting mode whereby thefailure does not influence motor driving unless the double failuresoccur thus largely enhancing reliability of the auxiliary artificialheart pump drive device.

The above-mentioned first and second processing circuits 210, 310 whichdetect failures occurring in the first and second pump control parts200, 300 preferably perform the failure detection processing describedhereinafter.

The function of the first processing circuit 210 of the first pumpcontrol part 200 or the function of the second processing circuit 310 ofthe second pump control part 300 which performs the detection processingof the failure in this embodiment may be realized by hardware orsoftware. Hereinafter, it is assumed that the function of the first orthe second processing circuit 210, 310 is realized by softwareprocessing.

FIG. 9 shows a block diagram of a constitutional example of the hardwareof the first processing circuit 210 of the first pump control part 200in this embodiment. Although FIG. 9 shows the constitutional example ofthe first processing circuit 210, the second processing circuit 310 ofthe second pump control part 300 may have the same constitution as FIG.9.

The first processing circuit 210 includes a CPU 500, an I/F circuit 510,a ROM (Read Only Memory) 520, a RAM (Random Access Memory) 530 and a bus540. The CPU 500, the I/F circuit 510, the ROM 520 and the RAM 530 areelectrically connected with each other via the bus 540.

For example, a program for realizing functions of the first processingcircuit 210 is stored in the ROM 520 or the RAM 530. The CPU 500 canrealize the functions of the first processing circuit 210 based onsoftware processing by reading the program stored in the ROM 520 or theRAM 530 and by executing the processing corresponding to the program.That is, with the use of the CPU 500 which reads the program stored inthe ROM 520 or the RAM 530 and performs processing corresponding to theprogram, the following processing is realized. Here, the RAM 530 is usedas a working area for the processing executed by the CPU 500 or is usedas a buffer area for the I/F circuit 510 or the ROM 520. The I/F circuit510 performs input/output interface processing between the firstprocessing circuit 210 and the pump drive processing circuit 400.

FIG. 10 is a flowchart showing a flow of a processing example of thefirst processing circuit 210 shown in FIG. 9. For example, in the ROM520 or the RAM 530 shown in FIG. 9, a program for realizing theprocessing shown in FIG. 10 is stored. The CPU 500 reads the programstored in the ROM 520 or the RAM 530 and executes the processingcorresponding to the program thus realizing the processing shown in FIG.10 based on software processing.

The first processing circuit 210 monitors a current IM₁ of the powersource line VL supplied to the first pump control part 200 via the firstpower source switch LDSW1, and determines whether or not the current IM₁of the power source line VL is an overcurrent of the power source lineVL at predetermined overcurrent detection timing (step S10).

When it is determined that the current IM₁ of the power source line VLis not in an overcurrent state in step S10 (step S10: N), the firstprocessing circuit 210 monitors a voltage VM₁ of the power source lineVL supplied to the first pump control part 200 via the first powersource switch LDSW1, and determines whether or not the voltage VM₁ ofthe power source line VL is an overvoltage of the power source line VLat predetermined overvoltage detection timing (step S12).

When it is determined that the voltage VM₁ of the power source line VLis not in an overvoltage stage in step S12 (step S12: N), the firstprocessing circuit 210 determines, at predetermined temperaturedetection timing, whether or not a temperature near the first invertercircuit 230 is a predetermined threshold temperature TP or more based ona sensing result of the first temperature sensor 250 (step S14).

When it is determined that the temperature near the first invertercircuit 230 is not the threshold temperature TP or more in step S14(step S14: N), the first processing circuit 210 returns to step S10 andcontinues the monitoring of the respective elements which become failurefactors again.

When the overcurrent is detected in the power source line VL at theovercurrent detection timing in step S10 (step S10: Y), the firstprocessing circuit 210 returns to step S10 to wait for a lapse of apredetermined detection period T1, and detects the presence or thenon-presence of an overcurrent in the power source line VL again (stepS16: N). Accordingly, when the first processing circuit 210 does notdetect the overcurrent in the power source line VL during the detectionperiod T1 from the overcurrent detection timing, the first processingcircuit 210 performs the detection of another failure factor. On theother hand, when the overcurrent is continuously detected in the powersource line VL even after the lapse of the detection period T1 from theovercurrent detection timing, the first processing circuit 210determines that a failure is detected, notifies the occurrence of afailure to the pump drive processing circuit 400 in response to adetection signal FAIL1 (step S18), and finishes a series of processing(end).

Accordingly, the erroneous detection of an overcurrent in the powersource line VL attributed to noises or the like and the detection of afailure attributed to an overcurrent in the power source line VL at alevel which does not obstruct the continued operation of the auxiliaryartificial heart system can be eliminated and hence, the auxiliaryartificial heart system can maintain high availability.

When the overvoltage is detected in the power source line VL at theovervoltage detection timing in step S12 (step S12: Y), the firstprocessing circuit 210 returns to step S10 to wait for a lapse of apredetermined detection period T2, and detects the presence or thenon-presence of an overcurrent in the power source line VL again (stepS20: N). Accordingly, when the first processing circuit 210 does notdetect the overvoltage in the power source line VL during the detectionperiod T2 from the overvoltage detection timing, the first processingcircuit 210 performs the detection of another failure factor. On theother hand, when the overvoltage is continuously detected in the powersource line VL even after the lapse of the detection period T2 fromovervoltage detection timing, the first processing circuit 210determines that a failure is detected, notifies the occurrence of afailure to the pump drive processing circuit 400 in response to adetection signal FAIL1 (step S22), and finishes a series of processing(end).

Accordingly, the erroneous detection of an overvoltage in the powersource line VL attributed to noises or the like and the detection of afailure attributed to an overvoltage in the power source line VL at alevel which does not obstruct the continued operation of the auxiliaryartificial heart system can be eliminated and hence, the auxiliaryartificial heart system exhibits high availability. Further, until thedetection period T2 elapses after the overvoltage in the power sourceline VL is detected at the overvoltage detection timing, the overcurrentin the power source line VL can be detected and hence, it is possible torapidly switch the system in response to an overcurrent which may becomea factor causing more serious failure than the overvoltage.

When it is detected that the temperature near the first inverter circuit230 is the threshold temperature TP or more at the temperature detectiontiming in step S14 (step S14: Y), the first processing circuit 210detects the presence or the non-presence of the overcurrent in the powersource line VL again to wait for a lapse of a predetermined detectionperiod T3 (step S24: N). Accordingly, when the first processing circuit210 does not detect that the temperature near the first inverter circuit230 is the threshold temperature TP or more during the detection periodT3 from the temperature detection timing, the first processing circuit210 performs the detection of another failure factor. On the other hand,when the first processing circuit 210 detects that the temperature nearthe first inverter circuit 230 is the threshold temperature TP or morecontinuously even after the lapse of the detection period T3 from thetemperature detection timing, the first processing circuit 210determines that a failure is detected, notifies the occurrence of afailure to the pump drive processing circuit 400 in response to adetection signal FAIL1 (step S26), and finishes a series of processing(end).

Accordingly, the erroneous detection of the temperature near the firstinverter circuit 230 attributed to noises or the like and the detectionof a failure attributed to a temperature change at a level which doesnot obstruct the continued operation of the auxiliary artificial heartsystem can be eliminated and hence, the auxiliary artificial heartsystem exhibits high availability. Further, until the detection periodT3 elapses after the first processing circuit 210 detects that thetemperature near the first inverter circuit 230 is the thresholdtemperature TP or more at the temperature detection timing, theovercurrent and the overvoltage in the power source line VL can bedetected and hence, it is possible to rapidly switch the system inresponse to an overcurrent and an overvoltage which may become factorscausing more serious failures than the temperature.

FIG. 11 is an explanatory view showing the detection periods T1, T2 andT3 in FIG. 10. FIG. 11 is provided for explaining the difference amongthe detection periods T1, T2 and T3 by aligning the detection starttimings of the respective detection periods with each other.

In FIG. 10, assuming the overcurrent detection timing as the detectionstart timing, the period until the detection determination timing atwhich a failure is detected in step S18 is set as T1 as described above,and this period corresponds to the detection period in which thepresence or the non-presence of the failure is detected based on theovercurrent in the power source line VL. In the same manner, assumingthe overvoltage detection timing as the detection start timing, theperiod until the detection determination timing at which a failure isdetected in step S22 is set as T2 as described above, and this periodcorresponds to the detection period in which the presence or thenon-presence of the failure is detected based on the overvoltage in thepower source line VL. Further, assuming the temperature detection timingas the detection start timing, the period until the detectiondetermination timing at which a failure is detected in step S26 is setas T3 as described above, and this period corresponds to the detectionperiod in which the presence or the non-presence of the failure isdetected based on the temperature near the first inverter circuit 230(first pump control part 200 in the broad meaning).

Here, as shown in FIG. 11, it is desirable that the respective detectionperiods satisfy the relationship of 0<T1<T2<T3. That is, by performingthe failure determination such that the detection period for detectingthe overcurrent becomes shortest among three kinds of detection periods,the system can be rapidly changed over in response to the failure factorwhich is unavoidable and is more serious thus enhancing the availabilityof the system. Further, by performing the failure determination suchthat the detection period for detecting the temperature near the firstinverter circuit 230 becomes longest among three kinds of detectionperiods, the order of priority is set low with respect to thecountermeasure against the temperature near the first inverter circuit230 which changes at a long cycle although a failure becomes seriousonce the failure occurs in this case. By lowering the order of prioritywith respect to the countermeasure against the temperature near thefirst inverter circuit 230, the rapid countermeasure can be takenagainst other failure factors so that the availability of the system isenhanced.

Although the explanation has been made with respect to the firstprocessing circuit 210 in FIG. 9 to FIG. 11, the second processingcircuit 310 also has the substantially equal constitution as the firstprocessing circuit 210 and can perform the substantially equalprocessing as the first processing circuit 210.

[Modification]

In this embodiment, as the drive device which exhibits high reliabilityand high availability, the explanation has been made with respect to theauxiliary artificial heart pump drive device for driving the auxiliaryartificial heart pump in the auxiliary artificial heart system. However,the present invention is not limited to the auxiliary artificial heartpump drive device. For example, the first and second pump control parts200, 300 and the pump drive processing circuit 400 in theabove-mentioned embodiment may be incorporated into a motor drive device(pump drive device) which requires high reliability and highavailability.

In this case, the motor drive device (pump drive device) which drives amotor (pump) includes first and second motor control parts arranged induplexed configuration where the respective motor control parts whichcontrol the motor by outputting a drive signal for driving the motor arearranged in duplexed configuration, and each motor control part has ameans which electrically cuts off a path through which theabove-mentioned drive signal is outputted to the motor when a failure isdetected in the motor control part.

Further, in the above-mentioned motor drive device, each motor controlpart may include a means which stops the supply of electricity to themotor control part when a failure is detected in the motor control part.

Further, in the above-mentioned motor drive device, the means whichstops the supply of electricity may be a unidirectional switch circuitwhich is connected to a power source line through which electricity issupplied to the motor.

Further, in the above-mentioned motor drive device, the unidirectionalswitch circuit may be constituted of a MOSFET.

Further, in the above-mentioned motor drive device, each motor controlpart may include a power amplifier which amplifies power of theabove-mentioned drive signal and a bidirectional switch circuit which isprovided between an output of the power amplifier and the motor, andwhen the first motor control part is in a normal state, thebidirectional switch circuit of the first motor control part may be setin a conductive state and the bidirectional switch circuit of the secondmotor control part may be set in a cut-off state, and when the firstmotor control part is in a failure state, the bidirectional switchcircuit of the first motor control part may be set in a cut-off stateand the bidirectional switch circuit of the second motor control partmay be set in a conductive state.

Further, in the above-mentioned motor drive device, the power amplifiermay be an inverter circuit.

Further, in the above-mentioned motor drive device, the bidirectionalswitch circuit may be constituted of a MOSFET.

Further, in the above-mentioned motor drive device, each motor controlpart may include a detection circuit for detecting a failure in themotor control part, and may electrically cut off a path through whichthe drive signal for driving the motor is outputted to the motor fromthe motor control part when the failure in the motor control part isdetected by the detection circuit.

Further, in the above-mentioned motor drive device, the detectioncircuit may detect a failure in the pump control part using at least onemonitoring result out of an overcurrent of a power source line forsupplying electricity to the motor drive device, an overvoltage of thepower source line and a temperature near the motor control part.

Further, in the above-mentioned motor drive device, assuming a detectionperiod for detecting the presence or non-presence of a failure based onthe overcurrent of the power source line as T1, a detection period fordetecting the presence or non-presence of a failure based on theovervoltage of the power source line as T2, and a detection period fordetecting the presence or non-presence of a failure based on thetemperature near the motor control part as T3, it is desirable that thedetection periods satisfy the relationship of T1<T2<T3.

Further, a motor system according to the present invention may include amotor and any one of the above-mentioned motor drive devices whichdrives the motor.

Although the auxiliary artificial heart pump drive device and theauxiliary artificial heart system (the motor drive device and the motorsystem) according to the present invention have been explained inconjunction with the above-described embodiments heretofore, the presentinvention is not limited to the above-mentioned embodiments, and thepresent invention can be carried out in various modes without departingfrom the gist of the present invention. For example, the followingmodifications can be considered.

(1) In the above-mentioned embodiments or the modifications thereof, theexplanation has been made by taking the auxiliary artificial heart pump(the pump incorporating the motor) having the constitution shown in FIG.2 as an example. However, the auxiliary artificial heart pump drivedevice and the auxiliary artificial heart system (motor drive device andmotor system) according to the present invention are not limited to theconstitution of the auxiliary artificial heart pump (pump).

(2) In the above-mentioned embodiments or the modifications thereof, theexplanation has been made by assuming that the pump such as theauxiliary artificial heart pump is the AC motor driven in response to athree-phase drive signal. However, the present invention is not limitedto the AC motor. The auxiliary artificial heart pump driven by theauxiliary artificial heart pump drive device according to the presentinvention (the motor driven by the motor drive device according to thepresent invention) may include a motor which is driven in response to adrive signal other than the three-phase signal or a DC motor, forexample.

(3) In the above-mentioned embodiments or the modifications thereof, theexplanation has been made with respect to the case where a failure isdetected based on three kinds of failure factors. However, the presentinvention is not limited to such a case. For example, a failure may bedetected based on at least one of the above-mentioned three kinds offailure factors. A failure may be detected based on four or more kindsof failure factors by adding other failure factors to theabove-mentioned three kinds of failure factors.

(4) In the above-mentioned embodiments or the modifications thereof, theexplanation has been made with respect to the case where the presentinvention is directed to the auxiliary artificial heart pump drivedevice and the auxiliary artificial heart system (motor drive device andmotor system). However, the present invention is not limited to suchdevices and systems. For example, the present invention may be directedto a drive method or a failure detection method of the auxiliaryartificial heart pump drive device (motor drive device) according to thepresent invention, a program in which processing steps of the drivemethod or the detection method for realizing the present invention aredescribed or a recording medium in which the program is recorded.

EXPLANATION OF SYMBOLS

-   10: auxiliary artificial heart pump-   11: drive part-   12: pump part-   13: impeller-   14: pump casing-   15: inlet port-   16: outlet port-   17: mechanical seal part-   20: control unit-   30: cable-   100: auxiliary artificial heart system-   200: first pump control part-   210: first processing circuit-   220: first gate driver-   230: first inverter circuit-   240: first switch circuit-   250: first temperature sensor-   300: second pump control part-   310: second processing circuit-   320: second gate driver-   330: second inverter circuit-   340: second switch circuit-   350: second temperature sensor-   400: pump drive processing circuit-   500: CPU-   510: I/F circuit-   520: ROM-   530: RAM-   540: bus-   CONT: auxiliary artificial heart pump drive device-   FAIL1, FAIL2: detection signal-   GD1, GD2: gate driver-   IM₁, IM₂: current-   LDSW1: first power source switch-   LDSW2: second power source switch-   PONT1: first pump drive control signal-   PONT2: second pump drive control signal-   PS: power source-   VM₁, VM₂: voltage

The invention claimed is:
 1. An auxiliary artificial heart pump drivedevice for driving an auxiliary artificial heart pump, the pump drivedevice comprising: a pump drive processing circuit; first and secondpump control parts arranged in duplexed configuration, each pump controlpart configured for controlling the auxiliary artificial heart pump byoutputting a drive signal to the auxiliary artificial heart pump,wherein said each pump control part has a detection circuit configuredto detect a failure state in the pump control part by using at least onemonitoring result selected from the group of: an overcurrent of a powersource line for supplying electricity to the auxiliary artificial heartpump drive device that exists for at least a period of time T1, anovervoltage of the power source line that exists for at least a periodof time T2, and a temperature near the pump control part that exists forat least a period of time T3, wherein the relationship T1<T2<T3 issatisfied, a switch circuit which, when the failure state is detected inthe pump control part, is configured to electrically cut off a paththrough which the drive signal is outputted to the auxiliary artificialheart pump, and a power source switch which, when the failure state isdetected in the pump control part, is configured to stop a supply ofelectricity to the pump control part, wherein when a normal state isdetected by the detection circuit of the first pump control part, theswitch circuit and the power source switch of the first pump controlpart are set in a conductive state by the pump drive processing circuitand the switch circuit and the power source switch of the second pumpcontrol part are set in a cut-off state by the pump drive processingcircuit, and when the failure state is detected by the detection circuitof the first pump control part, the switch circuit and the power sourceswitch of the first pump control part are set in the cut-off state bythe pump drive processing circuit and the switch circuit and the powersource switch of the second pump control part are set in the conductivestate by the pump drive processing circuit.
 2. An auxiliary artificialheart pump drive device according to claim 1, wherein the power sourceswitch is a unidirectional switch circuit connected to a power sourceline for supplying electricity to the auxiliary artificial heart pumpdrive device.
 3. An auxiliary artificial heart pump drive deviceaccording to claim 2, wherein the unidirectional switch circuit isconstituted of a metal oxide film semiconductor field effect transistor.4. An auxiliary artificial heart pump drive device according to claim 1,wherein each pump control part further includes a power amplifier whichis configured to amplify of the drive signal, and the switch circuit ofeach pump control part is a bidirectional switch circuit providedbetween an output of the power amplifier and the auxiliary artificialheart pump, and when the first pump control part is in the normal state,the bidirectional switch circuit of the first pump control part is setin the conductive state and the bidirectional switch circuit of thesecond pump control part is set in the cut-off state, and when the firstpump control part is in the failure state, the bidirectional switchcircuit of the first pump control part is set in the cut-off state andthe bidirectional switch circuit of the second pump control part is setin the conductive state.
 5. An auxiliary artificial heart pump drivedevice according to claim 4, wherein each of the power amplifiers is aninverter circuit.
 6. An auxiliary artificial heart pump drive deviceaccording to claim 4, wherein the bidirectional switch circuit isconstituted of a metal oxide film semiconductor field effect transistor.7. An auxiliary artificial heart system for assisting the flow of bloodin a heart, wherein the auxiliary artificial heart system comprises: anauxiliary artificial heart pump, and the auxiliary artificial heart pumpdrive device described in claim 1 for driving the auxiliary artificialheart pump.